The proposal addresses the development of T-cell immunotherapy using lentiviral -vector mediated anti-HIV RNA interence (RNAi) strategies. The assessment of any functional effect of RNAi on transduced T-cells or on the differentiation ofT-cells from stem cells will be an important goal of this proposal. Thus, the program will focus on T-cell models for evaluation of the safety of improved lentivims vectors with enhanced RNAi targeted to HIV, and will include a phase I clinical study evaluating the safety of lentivirus transduced T-cell immunotherapy. In addition, preclinieal research in animal models will address important questions relevant to stem cell-derived T-cell restoration in AIDS, especially how to perform efficient non-myeloablative autologous stem cell transplantation, how to select for transduced cells, and whether this approach provides protection from HIV or SHIV in these models. The consortium of academic and private sector investigators have exceptional research abilities in RNAi, in T-cell expansion, in detection of siRNA in transduced cells, in the SCID-hu model and the nonhuman primate transplantation model, and in cell-based gene transfer research. Finally, the development of a method for selection of T-cells from lentiviral vector-transduced stem cells in small animal and large animal models will provide the important information leading to eventual stem cellbased immune reconstitution in AIDS. Project 1: At BRICOH, J Rossi and collaborators at CSU (R. Akkina) and at Benitec Australia Ltd. (K. Reed) will focus on the development of optimized RNAi inhibition of HIV and will use a SCID-hu model to predict the overall clinical outcomes. Project 2: At BRICOH, J. K. Yee and collaborators at CSU (R. Akkina) will develop improved lentivirus vectors and study the function of T-cells after lentiviral vector mediated RNAi transduction and cell selection. Project 3: At FHCRC and the UW, H-P Kiem and colleagues will develop a test-of-concept of lentiviral vector modified stem cells transplantation and selection, with SHIV challenge, in a macaque model. Project 4: At BRICOH, J. Zaia and colleagues, and at UPENN (C. June) will conduct a phase I evaluation of lentivirus/RNAi safety using CD4-cell immunotherapy. The program is supported by 3 cores: the Administration Center (Core A) at BRICOH, the Antiviral Laboratory (Core B) at BRICOH, and the Clinical Resource Center (Core C) at International Therapeutics Inc. and at BRICOH.